The so-called "zombie rabbits" in Colorado are cottontail rabbits infected with Shope papillomavirus, causing horn-like
Residents in Fort Collins and surrounding areas have reported seeing rabbits with bizarre growths resembling horns, tentacles, or fangs, leading to comparisons with zombies or Frankenstein-like creatures
. These unusual appearances are caused by Shope papillomavirus (SPV), a virus specific to rabbits that produces wart-like tumors called papillomas, primarily around the face, head, and neck
Cause and Transmission
The virus is spread by biting insects such as mosquitoes, ticks, and fleas, and can also transmit between rabbits through direct contact
. Infection is seasonal, peaking in summer and fall when insect activity is highest
. The virus is a relative of human papillomavirus (HPV) and has been studied since the 1930s, but it does not infect humans or other animals
Most infected rabbits survive the infection, and the growths often disappear over time as the immune system fights the virus
. The growths are generally benign, though in rare cases they can develop into malignant tumors. They usually do not interfere with the rabbit’s ability to eat or drink
. Pet rabbits are more susceptible to severe effects, so owners are advised to keep outdoor rabbits away from wild populations during peak insect seasons
Safety and Precautions
Humans and other pets are not at risk from these rabbits
Do not touch or handle infected rabbits, especially domestic pets, to prevent transmission among rabbits
Observing from a distance is safe, and there is no need for panic despite their alarming appearance
The unusual growths may have inspired the jackalope legend, a mythical creature described as a rabbit with antelope-like horns, first reported by pioneers in the 1800s
. The current sightings are a real-world example of how viral infections can create fantastical appearances in wildlife.
In summary, the "zombie rabbits" of Colorado are a natural viral phenomenon affecting cottontail rabbits, creating striking but harmless growths, and are not a threat to humans or most pets
Why Rabbits Are Growing Horns And Tentacles In Colorado
https://cowboystatedaily.com/2025/08/17/what-the-heck-are-those-zombie-rabbits-found-just-south-of-wyoming-border/
What to Know About the Horned 'Zombie' Rabbits Hopping Around Colorado
https://time.com/7309600/zombie-rabbits-virus-colorado/
“Zombie” Rabbits With Freaky “Horns” Alarm Residents In Colorado – What ...
https://www.iflscience.com/zombie-rabbits-with-freaky-horns-alarm-residents-in-colorado-what-is-going-on-80412
Horn-like growth causes in rabbits
Viral infections affecting wild rabbits
Preventing rabbit papilloma infections
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